GB939533A - Circuit for unbalance detection apparatus - Google Patents

Abstract

939,533. Indicating rotary unbalance. STEWART - WARNER CORPORATION. June 14, 1960, No. 20927/60. Class 40 (1). [Also in Group XX] Spurious flashes from a stroboscopic lamp indicating the position of unbalance of a rotating body are avoided by supplying the lamp from a supply which, after a first operation of the lamp, is not immediately available for a second. As described, the wheel of a vehicle is raised off the ground and rotated to a speed above its natural resonant frequency. The wheel then freely decelerates and a stroboscopic lamp operated in synchronism with the wheel may be used to indicate the position of rotary unbalance which, at resonance leads the deflection by 90 degrees. As shown, the stroboscopic lamp 15 is controlled from an unbalance detector 13 of the type described in U.S.A. Specification 2,383,405. The detector consists of a magnet reciprocating relatively to a fixed coil to induce a voltage which passes through its peaks when the unbalance position is aligned with the magnet axis. The negative half-cycles of the detector output are selected by the diodeconnected left-hand side of a double triode. The signal developed at the diode load 6 is passed to the right-hand side of the triode through a resistance capacity combination 8, 9 which operates so that only a very narrow part each side of the maximum of the negative half-cycle passes to the next stage. The signal developed across the anode load 10 of diode 5 is fed through differentiating circuit 12, 13 to produce a very high spiked pulse at the grid of thyratron 14. The plate supply to the thyratron is determined from a voltage doubling circuit consisting of condenser 38, resistors 36, 37 and rectifiers 34, 35, feeding a supply condenser 21. This supply charges condenser 20 and feeds the plates of the stroboscopic discharge tube 15. When the spiked pulse triggers the thyratron it fires and its plate voltage falls. Condenser 20 discharges through the thyratron by way of the primary of pulse transformer 22, 24. The pulse developed in the secondary ionizes the gas in discharge tube 15 so that condenser 21 discharges through it, giving a brilliant flash. Because of the time required by the voltage doubling circuit to build up the voltage on condenser 21, tube 5 cannot fire at an undesired high frequency.